Why volunteer?

I doubt that potential contibutors wondering between LO and AOO will care much about the trademark. Most newcomers are here to scratch their own itch (fix a bug, implement a feature, etc) and will already have tried both AOO and LO. Even an hypothetical AOO-using company wanting to contribute will have to weigh a migration to LO against hiring somebody to fix AOO (and consider that LO bugfixes likely costs less than AOO bugfixes). Same dilema for the altruistic contributor who wants to improve the lives of "OpenOffice" users out there: maybe his energy would be better spent convincing/helping people to migrate to LO.

The trademark issue remains a big one, but trademark alone was not enough to retain/attract developers to AOO. However, trademark alone is the main reason why some LO contributors and some outside observers have strong negative feelings towards Apache/AOO. If openoffice.org simply redirected to LO, the hardships faced by AOO would hardly be newsworthy. But it'd make it clear that AOO has "lost" and is a very hard pill to swallow. If openoffice.org pointed to both LO and AOO, it could mend a lot of bridges and maybe ressurect cross-polination between the projects. Making oppenoffice.org a shared home would greatly reduce the flak received by AOO from various angles, and make Apache look like an enabler of the wider OpenOffice community rather than a failing member of it.